One supporter, emboldened as much by the quantity of drink he had consumed as the joy of the result, burst into the media room afterwards and, arms outstretched, bellowed: "Scotland! Scotland!"

There was an unashamed grandstanding to the moment, but few in the Scotland support feel the need to be timid.

Anxiety might normally have gripped some inside the stadium as long as the game remained at 0-0, but even in the midst of what became a grimly fought encounter, there was a resilient belief to the players and the crowd. That trait will be tested again when England come to Celtic Park on Tuesday, and old enmities are stirred, but there will be no intimidation amongst the home players or fans.

Strachan agreed quickly and firmly when asked if there would be changes to the starting line-up for the friendly. He was paying recognition to the way that some of his players had begun to run on empty in the closing stages against the Republic, having poured all of their industry and stamina into what was often a fiercely physical game.

England beat Scotland in a friendly last year

It was telling, for instance, that the best player on the pitch at Celtic Park - Charlie Mulgrew - looked heavy-legged in the closing exchanges. He had previously been sprightly in his movement and his instincts, and more than once side-stepped and jinked past his old Celtic teammate Aiden McGeady.

Under Strachan, the Scotland side has developed a clear sense of certainty. When they conceded the opening goal in Poland last month, the players merely knuckled down to the task in hand, and were duly rewarded with a draw. The same doggedness was evident against the Irish, when the game was so tightly balanced that tension might have constrained the home side.

Scotland are well-drilled under Strachan, so even in moments of fatigue or anxiety, habit becomes an ally. The players know what their basic duties are, and there are recognisable patterns to the team's play.

The strategies will be scrutinised by the challenge that England will pose, although it is natural to assume that the occasion will be dimmed a little by its proximity to such an important and draining competitive fixture as Friday's win.

Mostly, though, it will test the depth of Scotland's resources. The pool of accomplished talent does not run as deep as Strachan would wish in certain areas of the team.

Strachan may select Johnny Russell up front against England

He has always been particularly satisfied by the array of talent that his "small players" bring to the squad. Not for the first time, the work-rate and willingness to try to weave coherent passing moves and to run at defenders with intent and guile, was evident among the three figures who lined up behind the central striker at Celtic Park.

The likes of Graham Dorrans, Chris Burke, Barry Bannan and Johnny Russell will come into the reckoning, although if Strachan could dismiss the physical effects of the Republic game then he would surely continue to pick Steven Naismith, goalscorer Shaun Maloney and Ikechi Anya.

They ran hard and harried opponents throughout the game - with none of them limited to a particular position or role once Scotland were moving forward - and Naismith's ability to drop into pockets of space to collect the ball and initiate attacks was vital to Scotland's cause.

Maloney, in particular, is always capable of a moment of refined talent and for all that his decisive goal was built on a training ground routine devised by former Motherwell manager Stuart McCall, it still needed the clinical but exquisite touch.

Strachan lauded "bravery on the ball", but Scotland's composure in possession and willingness to be patient even as they moved into the final third - probing for space rather than hurling crosses into the penalty area - was just as significant.

Steven Fletcher was withdrawn during Friday's win over Republic of Ireland

The injury to Steven Fletcher exposed a limitation, though, since his replacement Chris Martin was less mobile and less technically adept. Strachan could play Stevie May up front against England, and the Sheffield Wednesday striker certainly plays with a fearless and bullish air, but Martin is more likely to start.

Yet without Fletcher's ability to take possession with his back to goal, then spin into space or move the ball swiftly to team-mates on either flank, Scotland's play is less cohesive, more one-dimensional.

There was strength as much as poise in central midfield, where Scott Brown's bristling and compulsive energy was a constant driving force, but he and Mulgrew will have been drained by the contest. Darren Fletcher could step up to the starting line-up, but there seems to be less vigour to his movement on the ball since his return from illness.

The game against England, with all of its history and traditional edge, will explore the limits of this Scotland squad. It will be pleasing for Strachan, though, that development is evident.

The progress of Andrew Robertson is, for instance, a source of promise. He grew into the game against the Republic, and often seemed the coolest head, as well as the surest touch, in the Scotland defence in the second half. He was more involved in attack during the first half, where his ability to whip in crosses on the overlap was a menacing option.

No Scotland side can ever dismiss a meeting with England, even if this occasion is far less important or influential than recent competitive fixtures. Momentum as well as mood is at stake.

Strachan has brought confidence to Scotland, and allowed fans to be hopeful rather than fearful. The optimism has been hard-won, and an encouraging display against England will feed it further.